The present disclosure relates to a high voltage direct current (HVDC) transmission system and a control method thereof, and more particularly, to an HVDC transmission system and a control method thereof that may detect an abnormal voltage on a DC transmission line.
High voltage direct current (HVDC) transmission indicates converting alternating current (AC) power produced at a power station into DC power by a transmission site to transmit the DC power, and then re-converting the DC power into the AC power by a reception site to supplying the AC power.
An HVDC transmission system is applied to submarine cable power transmission, large-amount long-distance power transmission, interconnection between AC systems, etc. Also, the HVDC transmission system enables different frequency systems interconnection and asynchronism interconnection.
The transmission site converts the AC power into the DC power. That is, since transmitting the AC power by using a submarine cable is significantly dangerous, the transmission site converts the AC power into the DC power to transmit the DC power to the reception site.
In this case, the transmission site transmits the DC power to the reception site through a transmission line. However, when there is an abnormal DC flowing on the transmission line or there is an abnormal voltage across the transmission line, i.e., when there is an overcurrent or overvoltage on the transmission line, an HVDC transmission system may be damaged.
Thus, there is a need to quickly detect an abnormal state on the transmission line and cope with the state.